Exhaust emission control means for internal combustion apparatus

ABSTRACT

An exhaust emission control means for removing smog producing constituents from the exhaust gases of an internal combustion chamber is disclosed which employs a membrane gas separator disposed in gas communication with the flow of exhaust gases at essentially atmospheric pressure. The gas separator causes unburned hydrocarbons and other smog producing constituents of the exhaust gas to go into solution with the membrane material, which is a barrier to permanent gases, and to diffuse from the membrane material into a stream of fresh air at substantially atmospheric pressure which is thence fed back to the combustion chamber or to an afterburner for completing the combustion of such smog producing constituents. A relatively large area of membrane material is provided in a relatively small volume by pleating or folding the membrane. Alternatively, a large area membrane is provided in a small volume by bonding together adjacent sheet portions of membrane in a certain pattern of bond lines to provide a honeycomb of alternating exhaust and fresh air gas passageways when the bonded structure is expanded.

Unite States Patent Aine EXHAUST EMISSION CONTROL MEANS FOR lNTERNALCOMBUSTION APPARATUS [76] Inventor: Harry E. Aine, 4008 Twyla Lane,

Campbell, Calif. 95008 [22] Filed: June 14, 1971 21 Appl. No.: 152,676

[52] US. Cl. 55/158, 55/DlG. 30, 60/279,

210/321, 210/493 [51] Int. Cl B0ld 13/00 [58] Field of Search 60/278,279, 297,

60/311; 123/119 A;55/16, 158, DIG. 30; 23/277 C; 210/321, 493

[56] References Cited UNITED STATES PATENTS 3,025,964 3/1962 Summers210/493 3,458,977 8/1969 210/493 2,597,907 5/1952 Steiner 55/1582,966,235 12/1960 Kammermeyer 55/16 3,241,293 3/1966 Pfefferle 55/163,266,223 8/1966 Dresser 55/158 3,339,341 9/1967 Maxwell 55/16 3,401,7989/1968 Nyrop... 210/321 3,580,840 5/1971 Uridil..... 210/321 3,612,28110/1971 Leonard 210/321 Primary ExaminerDoug las Hart Attorney-Harry E.Aine and William J. Nolan [57] ABSTRACT An exhaust emission controlmeans for removing smog producing constituents from the exhaust gases ofan internal combustion chamber is disclosed which employs a membrane gasseparator disposed in gas communication with the flow of exhaust gasesat essentially atmospheric pressure The gas separator causes unburnedhydrocarbons and other smog producing constituents of the exhaust gas togo into solution with the membrane material, which is a barrier topermanent gases, and to diffuse from the membrane material into a streamof fresh air at substantially atmospheric pressure which is thence fedback to the combustion chamber or to an afterburner for completing thecombustion of such smog producing constituents. A relatively large areaof membrane material is provided in a relatively small volume bypleating or folding the membrane. A1- tematively, a large area membraneis provided in a small volume by bonding together adjacent sheetportions of membrane in a certain pattern of bond lines to provide ahoneycomb of alternating exhaust and fresh air gas passageways when thebonded structure is expanded.

2 Claims, 17 Drawing Figures DESCRIPTION OF THE PRIOR ART Heretofore,exhaust emission control devices have been proposed wherein the exhaustgases from an internal combustion engine have been fed through acentrifugal separator for separating the heavy constituents of theexhaust from the lighter constituents. The lighter constituents wererecycled to the engine and utilized therein, whereas the heavierconstituents were disposed of. Such a prior art teaching is disclosed inU.S. Pat. No. 2,147,670 issued Feb. 21. 1939.

In another prior art method for cleaning engine exhaust gases, theexhaust gases of an internal combustion engine were fed through ascrubber unit which was packed with a fibrous or spherical body packingmaterial over which raw fuel was sprayed and gravitated in a flow contrato the flow of exhaust gases through such packing material. The raw fuelpicked up unburned hydrocarbons and thereby scrubbed the exhaust gases.The raw fuel was collected at the bottom of the. scrubber and fed to thecombustion chamber for burning. Such a prior art method is disclosed inU.S. Pat, No. 3,100,376 issued Aug. 13, 1963.

It is also known from the prior art that a membrane gas separator may beutilized for separating condensable gaseous hydrocarbons from permanentgases by flowing the gas stream containing the hydrocarbons over oneface of a membrane which is made of a material which will take thehydrocarbons into solution. A total pressure differential is maintainedacross the membrane to allow the hydrocarbon gases to diffuse throughthe membrane to the opposite side while excluding permanent gases.Examples of such membrane gas separators for use in gas analyzer inletsystems for evacuated gas analyzers, such as mass spectrometers, etc.,are disclosed in U.S. Pat. No. 3,455,092 issued July 15, 1969 and U.S.Pat. No. 3,429,105 issued Feb. 25, 1969.

Membrane gas separators have also been employed for reclaiming heliumand CO, from methane gas as disclosed in U.S. Pat. No. 3,256,675 and forseparating CO from permanent gases by means of a silicone rubbermembrane as disclosed in U.S. Pat. No. 2,966,235 issued Dec. 27, 1960.Both of these references maintained a substantial total pressuredifferential across the membrane.

SUMMARY OF THE PRESENT INVENTION combustion chamber or by being fed toan afterburner.

In another feature of the present invention, the membrane gas separatorincludes a membrane made of a material which has a permeability forpermanent gases which is substantially less than its permeability forsmog producing gaseous constituents.

In another feature of the present invention, the membrane gas separatorincludes a membrane made of a material selected from the groupconsisting of polymers and stationary liquid phases.

In another feature of the present invention, the membrane strudture ofthe gas separator incudes a perforated support structure mounted insupportive engagement with the membrane for supporting the membrane.

In another feature of the present invention, the membrane gas separatoris pleated to provide a large area of membrane in contact with theexhaust gases for increasing the rate of transfer of smog producingconstituents across the membrane of the gas separator.

In another feature of the present invention, a heat exchanger isdisposed in heat exchanging relation with the flow of the exhaust streamupstream of the gas separator for cooling the exhaust gases fed to thegas separator.

In another feature of the present invention, the membrane gas separatorincludes a membrane made of silicone rubber.

In another feature of the present invention, a narrow tubular membraneor a pair of closely spaced membrane sheets are wound or folded togetherwith a relatively narrow spacing between adjacent turns or folds toprovide two systems of adjacent gas passageways separated by themembrane.

In another feature of the present invention, a membrane is stacked orfolded and adjacent membrane portions are bonded together in accordancewith a predetermined bond line pattern such that when the structure isexpanded it forms a honeycomb array of adjacent gas passagewaysseparated by the membrane. Two gas manifold systems are connected intothe array of gas passageways for providing two adjacent systems of gaspassageways separated by the membrane material.

In another feature of the present invention, a single sheet of membranematerial is folded and closed off on opposite sides to define twosystems of gas passageways separated by the membrane material.

Other features and advantages of the present invention will becomeapparent upon a perusal of the following specification, taken inconnection with the accompanying drawings, wherein:

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic line diagram,partly in block diagram form, of a combustion device incorporating anexhaust emission control means of the present invention,

FIG. 2 is an enlarged longitudinal sectional view of the membrane gasseparator portion of the structure of FIG. 1 delineated by line 2-2,

FIG. 3 is a schematic sectional view of the structure of FIG. 2 takenalong line 3-3 in the direction of the arrows,

FIG. 4 is a schematic sectional view of the structure of FIG. 2 takenalong line 4-4 in the direction of the arrows,

FIG. 5 is a schematic sectional view of the strudture of FIG. 2 takenalong line 5-5 in the direction of the arrows,

FIG. 6 is a schematic longitudinal sectional view of an alternativeembodiment of the membrane gas separator of FIG. 1 delineated by line6-6,

FIG. '7 is a reduced sectional view of the structure of FIG. 6 takenalong line 7-7 in the direction of the arrows,

FIG. 8 is a schematic cross-sectional view of an alternative embodimentof the present invention,

FIG. 9 is a sectional view of the structure of FIG. 8 taken along line99 in the direction of the arrows,

FIG. 10 is a view similar to that of FIG. 8 depicting an alternativeembodiment of the present invention,

FIG. 11 is a view similar to that of FIG. 8 depicitng another embodimentof the present invention,

FIG. 12 is a sectional view of the strcture of FIG. 11 taken along line12l2 in the direction of the arrows,

FIG. 13 is a sectional view of the structure of FIG. 11 taken along linel313 in the direction of the arrows,

FIG. 14 is a view similar to that of FIG. 8 depicting an alternativeembodiment of the present invention,

FIG. 15 is a sectional view of the structure of FIG. 14 taken along linel5-15 in the direction of the arrows,

FIG. 16 is a fragmentary sectional view of a portion of the structure ofFIG. 14 delineated by line 16-16 and depicting an alternative embodimentof the present invention, and

FIG. 17 is a sectional view of a porous tube coated with membranematerial for defining an alternate embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to FIG. 1, thereis shown an internal combustion device 1 incorporating an exhaustemission control means of the present invention. More particularly, aninternal combustion chamber 2 is supplied with air and fuel via inputport 3 for combustion within the combustion chamber 2. The combustionchamber may comprise, for example, one or more of the internalcombustion chambers of, an automotive engine, a jet engine, a furnace,an incinerator, or the like. The combustion products are exhausted fromthe combustion chamber 2 via an output port 4 and vented to theatmosphere via the intermediary of an exhaust pipe 5.

A membrane gas separator 6 is connected in stream with the flow ofexhaust gases thruogh the exhaust pipe 5 for separating certainundesired smog producing gaseous combustion product constiuents of theexhaust gases. More particularly, the exhaust gases of the typicalinternal combustion engine include, aside from nitrogen, carbon dioxide,and carbon monoxide, numerous unburned hydrocarbons including, methane,ethane, ethylene, acetylene, propane, propylene, isobutane, C olefins,isopentane, n-pentane,. 2- methylpentane, 2,3-dimethylbutane,3-methylpentane, n-hexane, l-hexene, methylcyclopentane, 2-methylhexane, 2,3-dimethylpentane, benzene, 3-

heptene, and 3-methyl-2-hexene.

The amount and proportion of the various unburned hydrocarbons vary withthe operation of the autombile. For example, when the automobile isidling, the total unburned hydrocarbons may comprise, for example, 1,815parts per million by volume. When the automobile is accelerating to 30miles per hour, the total unburned hydrocarbons may comprise only 670parts per million. When crusing at 30 miles per hour, the unburnedhydrocarbons account for approximately 919 parts per million, whereaswhile the automobile is decelerating from 30 miles per hour the amountof unburned hydrocarbons vastly increases to 6,534 parts per million.According to current theory, hydrocarbons photochemically react in theatmosphere to form objectionable air pollutants.

Many of the unburned hydrocarbon constituents of the exhaust gas suchas, C C C and C hydrocarbons are readily removed from the exhaust gasesby means of the membrane gas separator 6. These separated unburnedhydrocarbons are transferred into the filtered input fresh air stream tothe combustion chamber 2. The input fresh air is filtered by amechanical filter 7 to remove particulate matter which may tend to clogor obstruct operation of the membrane. The transferred unburnedhydrocarbons are fed with input air stream to the combustion chamber 2for burning therein. As an alternative, the separated unburnedhydrocarbons may be eliminated or disposed of by being fed to anafterburner, not shown.

A heat exchanger 8, which may comprise a multitude of thermallyconductive fins projecting into both the exhaust stream and the inputair stream to the'combustion chamber, serves to reduce the temperatureof the exhaust gases as fed to the membrane gas separator 6. In atypical example, the membrane gas separator 6 is preferably operated atan operating temperature below 400C and preferably approximately 250C.The heat exchanger 8 is required only as necessary to reduce theoperating temperature of the separator 6 to a temperature within itsoperating range.

The membrane gas separator 6 includes an exhaust chamber 9 through whichthe exhaust gases are fed and a separator chamber 11 into which theseparated gaseous constituents are fed. Chambers 9 and 11 are separatedby means of a membrane separator 12. The separator chamber 11 preferablyhas an input port and an output port for passing an air streamtherethrough to pick up the separated gaseous constituents and to carrysuch constituents to the combustion chamber 2. As an alternative, notshown, the separator chamber 11 need only have an exhaust port which isevacuated by means of a pump which then pumps the gases removed from theseparator chamber 11 to the combustion chamber 2 for burning. I

The effectiveness of membrane 12 in separating unburned hydrocarbons andcertain other materials such as N 0 CO N0 and S0 from other andpermanent gas constituents of the exhaust gases, such as N CO, 0, andNO, is influenced by the material of the membrane, the thickness of themembrane, the temperature of the membrane, and the area of the membrane.

Suitable membrane materials are those materials selected from the classconsisting of polymers and stationary liquid phases, where the termstationary liquid phase is used in the same sense as that employed forpartitioning of gases in gas chromatography. In those instances where atruly liquid stationary liquid phase forms the membrane 12, a suitablereservoir supporting structure must be provided. For example, areservoir constructed from a porous glass membrane or a fine screen meshwhich is capable of supporting the liquid membrane by surface tensionwould be suitable. The membrane 12 operates by causing the organicvapors to go into solution with the membrane material. The dissolved gasdiffuses through the membrane 12. Permanent gases do not condense on themembrane 12. As utilized herein, entering into solution is defined as aprocess of condensation and then mixing of the gaseous material in thesurface layers of the membrane 12. (See Physics and Chemistry of theOrganic Solid State, edited by David Fox, Mortimer M. Labes and ArnoldWeissberger, published by Interscience Publishers,

New York, 1965, Volume 2, page 517.) Stationary liquid phases are thoseliquid material employed in chromatographic columns to partitionmaterials to be separated. Comprehensive lists of such membranematerials can be found in numerous publications, one being GasChromatography by Ernst Bayer, published by Elsevier Publishing Company,New York, 1961, tables 2, l3 and 14.

The membrane 12 or barrier is typically thin and can be called amembrane. in a typical example, the membrane is constructed of anelastomer, namely silicone rubber, having a thickness between 0.001 inchand 0.0001 inch. The basic property of this membrane 12 is its action inthe manner of a liquid phase. More particularly, the permanent gaseshaving the unburned hydrocarbon or organic vapors entrained therein comeinto contact with the membrane 12. Partition takes place. The absorptionenergy for the permanent gases is so small that very little goes intosolution. The permeability of the membrane 12 for a given gaseousconstituent is determined by two quantities, the solubility and thediffusion rate for the given gaseous constituent. The product of thesefor the permanent gases is very small, even though diffusion for suchgases can be very rapid. For the organic vapor, the large solubilityresults in a large permeability and so organic vapor is transmittedthrough membrane 12 readily to the opposite side.

For hydrocarbon gases in the range of C C the permeability factor isapproximately 1,000 times greater than that for permanent gases such asnitrogen. N 0

and CO gases have a permeability factor of approximately times that ofthe permanent gases, whereas NO and S0 have permeability factors ofapproximately '50 times that of the permanent gases.

The permeability P of the membrane 12 for any given gas can becalculated from a knowledge of its diffusion rate and solubility. Therelationship is where S is the solubility for the gas, D is thediffusion rate for the given gas, A is the area of the membrane, .P p,,,is the partial pressure differential across the membrane for theparticular gaseous constituent, d is the thickness of the membrane and zis the time.

Assuming a silicone rubber membrane 12 approxi mately 0.001 inch inthickness and a 4 liter internal combustion engine 2 operating at 3,000rpm it is estimated that approximately 20 square meters of membrane 12would be required to remove substantially all of the unburnedhydrocarbons from the exhaust gases. Such a membrane may comprise merelythe free standing silicone membrane 12 or the membrane may be supportedby being coated onto a dacron web or cloth and folded in an accordianpleated geometry, as more fully disclosed below. For example, such apleated geometry, having a period for-each pleat of 10 times thethickness of the membrane, a depth of each pleat of approximately 5inches, and a width of each pleat of 6 inches, and a length for thepleated geometry of approximately 2 feet, yields approximately l30square yards of membrane material in contact with the exhaust gas flow.

Although the separation chamber 11 may be closed except for an exhaustport, such that a reduced pressure is drawn on the separation chamber 11via a pump, not shown, for removing the separated gas, this geometry isnot preferred because it complicates obtaining a proper support for alarge area membrane. The preferred embodiment flows the air intake tothe combustion chamber 2 through the separation chamber 111 of themembrane gas separator 6 and operates on the principle of a differentialin the partial pressure of the gaseous constituents without asubstantial difference in the total pressure across the membrane 12.

The concentration of the unburned hydrocarbons in the fresh air intakestream to the combustion chamber 2 will be at ambient levels, andtherefore very low, whereas the unburned hydrocarbon concnetration inthe exhaust stream can be on the order of thousands of parts permillion. Thus, a very substantial partial pres sure differential isestablished across the membrane 12 for the gaseous constituents ofinterest without the necessity of a total pressure differentialthereacross.

Thus, the unburned hydrocarbons which go into solution with the membranematerial and diffuse therethrough to the separation chamber 11 aretransferred from the exhaust stream to the air intake stream to thecombustion chamber 2, thereby greatly simplifying the support for thelarge area membrane 12 and allowing a relatively large area membrane tobe placed within a relatively small volume.

Referring now to FIGS. 25 there is shown one physical realization forthe membrane gas separator 6. More particularly, the membrane gasseparator 6 includes a generally rectangular enclosure 14 having anupper gas separation chamber 11 partitioned from a lower gas inputchamber 9 via the intermediary of a pleated gas separating membrane 12as of silicone rubber 0.001 inch- 0.001 inch thick. An array oftransversely di* rected baffles 18 are placed in the separation chamber11 for directing the flow of fresh air across the membrane separator 12in a plurality of parallel directed flow paths interconnecting an inputmanifold 16 and a collection manifold 17. The input distributionmanifold 16 receives air from the air filter, directs this air flowacross the membrane separator 12 to the collection manifold 17. Theoutput air stream of the collection manifold 17, which now contains theunburned hydrocarbons is directed back to the combustion chamber 2 viaintake pipe 18.

The membrane separator 12 is supported on a plurality of longitudinallydirected rods or support members 119 (FIG. 4) which extend transverselyto the direction of the pleats. The support rods 19 are positioned bothabove and below the membrane 12. In addition, in a preferred embodiment,an array of support wires or strings, as of 0.001 inch to 0.0001 inchdiameter are positioned, with one wire, within each of the apexes of thepleats. The arrays of transverse wires on opposite sides of the pleatedmembrane are spring biased apart to retain the proper pleat shape andspacing in the pres ence of small total pressure differentials acrossthe membrane 12.

The input exhaust gas chamber '9 (FIG. 5) includes a plurality oftransversely directed inter-digitated baffles 211 which are arranged tocause the flow of exhaust gases to traverse a winding path back andforth over the membrane separator 12. Exhaust gases to be separated arefed to the chamber 9 via input port 22 and the exhaust gases, free ofunburned hydrocarbons, are ex hausted to the atmosphere via exhaust port25.

Although, in the membrane gas separator construction of FIGS. 2-5, theseparated gas flow has been ar ranged to flow transversely across themembrane 12 in a plurality of parallel paths such that fresh air isintro-' duced all along the length of the membrane 12, this is not theonly suitable air flow pattern. More particularly, in an alternativeembodiment, the gas separator chamber 11 would have a baffle arrangementsubstantially the same as that provided for the exhaust gas chamber 9with the flow of fresh air being in the opposite direction to that ofthe exhaust gases. However, if the flow of the fresh air stream isexactly parallel to the exhaust gas stream and the flow in both streamsis equal then only a maximum of 50 percent of the unburned hydrocarbonsmay be transferred from the exhaust gas stream to the fresh air stream,assuming no total pressure drop across membrane 12.

Referring now to FIGS. 6 and 7 there is shown an alternative physicalrealization of the membrane gas separator 6. In this embodiment, the gasseparating membrane 12 is folded into an accordian pleated geometry withthe pleats running longitudinally of the membrane separator 6. Thepleated membrane 12 is then formed into a cylinder so that the inside ofthe cylindrical pleated membrane 12 defines the separated gas chamber 11and an annular region surrounding the outside of the membrane 12 formsthe exhaust gas input chamber 9. The membrane 12 is sealed across theends of a cylindrical envelope 26. Helical baffles 27 extend inwardlyfrom the envelope 26 into the exhaust gas input chamber 9 causing theexhaust gases to spiral around the outside of the membrane separator 12for increasing the time the exhaust gases are in contact with themembrane 12. Fresh air is directed through the center separated gaschamber 11 for removing the separated unburned hydrocarbons and forcarrying same to the combustion chamber 2.

Referring now to FIGS. 8 and 9, there is shown an alternative physicalrealization of the relatively large area membrane separator 6. In thisinstance, the membrane 12 is formed into a long tubulargeometry ofnarrow cross-section. More particularly, two sheets of membrane 12 areselaed at their edges and folded back and forth into a serpentinestructure with adjacent folds of the tube being separated by means of acorrugated sheet separator 35 to define a multitude of tubular gaspassageways orthogonally directed to the direction of gas flow throughthe folded tube.

A plurality of rods 36 are'inserted into the ends of the corrugatedmembers 35 such rods being supported from the end walls 37 of theseparator 6- for assuring the proper positioning of the corrugatedseparators 35 relative to the folds of the tubular membrane 12. Gasinlet and outlet manifolds 38 and 39 are provided at opposite ends ofthe corrugated separator 35 in gas communication with the passagewaysdefined within the corrugated separator 35.

The exhaust gases are directed through the folded tubular membrane 12.The fresh air intake to the combustion chamber flows through thecorrugated separator structure 35. Alternatively, the exhaust gases maybe directed through the corrugated structure 35 with the fresh air flowto the combustion chamber flowing through the folded tube 12.

Referring now to FIG. there is shown a membrane gas separator structure6 similar to that of FIGS. 8 and 9 with the exception that the tubularmembrane 12, instead of being folded, is wound into a spiralconfiguration with the corrugated separator 35 disposed between adjacentturns of the tubular membrane 12. At the interior of the spiral, thetubular membrane 12 is placed in gas communication with a hollow tube 41extending axially of the spiral wound tube 12. Axially directed rods 36extend inwardly from the end walls of the separator 6 through the inputand output manifolds 38 and 39 into the convolutions of the corrugatedseparator 35 to assure proper spacing of adjacent turns of the separatorstructure 35 and tube 12.

Referring now to FIGS. 11-13, there is shown an alternative physicalrealization for the membrane separator 6 incorporating features of thepresent invention. The structure is similar to that of FIGS. 8 and 9with the exception that the membrane 12 comprises merely a singlemembrane sheet folded back and forth on itself with the longitudinalside edges of the folded membrane being sealed in a gas tight manner tothe longitudinal side walls 42 and 43 of the separator 6. In thismanner, a multi-layer separator structure is obtained similar to that ofFIGS. 8 and 9 with the exception that the corrugated separators 35 arepositioned between each fold of the membrane 12 to provide two systemsof parallel tubular gas passageways extending lengthwise of theseparator 6. I

Alternate layers of the partitioned folds are connected together viainput and output manifolds 44 and 45 into the exhaust gas stream to formone system of gas passageways which includes every other layer of thefolded membrane structure. The second system of gas passageways includesthe alternate set of layers of the folded membrane 12. However, in thiscase, the corrugated partitions 35 are beveled at opposite ends 46 and47 to mate with similarly beveled ends of transversely directedcorrugated partitioning members 48 and 49 to form miter jointstherebetween. The partitioning members 48 and 49 extend throughapertures in the sidewall 42 of the separator 6 to respective input andoutput manifolds 51 and 52 connected in series with the air stream tothe combustion chamber.

Referring now to FIGS. 14 and 15, there is shown an alternative physicalrealization of the membrane gas separator 6. In this embodiment, asingle membrane sheet 12 is folded back and forth on its self or cutinto sections and stacked. Adjacent layers of the stack are printed withbond lines 53 of adhesive extending across the width of the sheet 12.The bond lines 53 between adjacent pairs of layers are staggered suchthat when the sheets are bonded together at the bond lines 53 and thestructure is expanded, as by pulling from the top and bottom of thestack, the structure expands to form a honeycomb structure, as shown inFIG. 14. Each of the honeycomb tubular members is of generally a foursided configuration. The outside edges of the honeycomb are bonded tothe side walls 54 of the gas separator 6.

An array of tubular members 55 as of metal or glass, are inserted intoalternate tubular passageways in the honeycomb structure as indicated bythe unshaded squares of FIG. 14 for manifolding the honeycomb structure.The manifolding tubes 55 are conveniently inserted into the honeycombstructure by pressurizing the honeycomb structure to cause it to expandin size, and then inserting the tubes 55 from opposite ends into thehoneycomb and reducing the pressure to allow the individual tubularportions of the honeycomb to collapse upon and grip the outside of thetubes 55. An adhesive is preferably provided around the outside of thetubes 55 as inserted-into the honeycomb structure for bonding thehoneycomb material to the manifold tubes 55.

The outside ends of the manifold tubes 55 are sealed through aperturesin baffle plates 56 at opposite ends of the honeycomb to define inputand output fresh air manifolds 57 and 58 at opposite ends of the gasseparator structure 6. The exhaust input and output manifolds 59 and 61are defined by the spaces between the baffle plates 56 and the oppositeends of the honeycomb structure.

The honeycomb structure of FIGS. 14 and 15 is preferably oriented suchthat the tubular portions of the honeycomb extend in the verticaldirection. The exhaust gas stream is preferably directed through theinside manifold chambers 59 and 61 such that the tubular manifoldingmembers 55 do not tend to constrict the flow of exhaust gases throughthe tubular portions of the honeycomb. In this manner, carbon particlesand the like which may tend to collect within the exhaust gas channelsof the honeycomb can drop through the structure to the collectionmanifold 61.

In a typical embodiment of the honeycomb structure of FIGS. 14 and 15, ahoneycomb which is inches deep, in the direction of gas flow, 16 incheswide and 3 feet long will provide approximately 20 square yards of gasseparator membrane 12 when the tubular portions of the honeycomb are ofrectangular cross-section and approximately one-fourth inch on thediagonal. If the diagonal dimension is reduced to one-eighth inch,approximately 40 square yards of membrane material will be incorporatedin the same volume.

Referring now to FIG. 16, there is shown an alternative embodiment tothe structure of FIGS. 14 and 15 wherein the adhesive bond line patternsare arranged such as to produce a honeycomb wherein the tubular portionsare of hexagonal cross section.

An advantage of the multi-layered membrane configurations with systemsof elongated parallel tubular gas passageways is that the effect of atear or break in the membrane is localized such that the overallperformance of the gas separator 6 is not appreciably impaired.

Although the large area membrane separator configurations of FIGS. 2-16have been disclosed for use in separating smog producing constituentsfrom the flow of exhaust gases from a combustion chamber, theseconfigurations are useful in general for gas separation. The separatedgases need only be collected and disposed of, as by absorption in amolecular sieve material disposed on the separated gas collection sideof the membrane. In such a case the membrane serves as a selector forselectively separating certain gases for application to the molecularsieve material. Suitable molecular sieve materials include activatedcarbon and other well known gas absorbing materials.

Although preferred embodiments of the present invention utilize eitherfolded, pleated, or honeycomb membrane geometries, other membranegeometries having a relatively large surface area may be utilized. Forexample, a multitude of hollow porous pipes, as of glass, may be coatedon their exterior surface with a very thin film of membrane material andthe glass pipes may extend into or through the flow of exhaust gases.The tubes have their interiors connected in gas communication with acollection manifold 17 or with input and output manifolds 16 and 17 forpassing the fresh air intake stream therethrough for transfer of theunburned hydrocarbons from the exhaust gas stream to the fresh airstream. Such tubes may have a star or fluted cross sectionalconfiguration as shown in FIG. 17, for increasing the surface area ofthe membrane exposed to the exhaust gases.

An advantage to the membrane separator configurations of FIGS. 2-16 isthat the membrane 12 is relatively soft, to absorb sounds and vibrationsin the exhaust gas flow, such that the membrane gas separator 6 alsoserves as a muffler for muffling the exhaust noises. Also the vibrationand sound absorbed by the membrane structure 12 will tend to break loosecollections of carbon material on the membrane 12, in the manner of adeicing boot.

If the exhaust gases contain a substantial amount of particulate matterwhich may tend to coat the membrane 12, a suitable filter may be placedup stream of the membrane separator in the exhaust pipe 5 for removingsuch particulate matter.

What is.claimed is:

1. In a membrane fluid separator:

membrane means formed into a multi-layer structure having first andsecond systems of adjacent fluid passageways, said adjacent systems offluid passageways being separated from each other by a web of membranematerial; first fluid manifold means for connecting said first system ofsaid passageways in fluid communication with a fluid stream containingfluid to be separated therefrom for contacting a first side of saidmembrane with the fluid to be separated; fluid collecting means in fluidcommunication with the second side of said membrane means for collectingthe separated fluid constituent;

exhaust passage means for removing the remaining portion of said fluidstream from said first system;

said multi-layer membrane structure comprising a honeycomb structure fordefining a multitude of parallel tubular passageways of said first andsec- -ond system of fluid passageways, and wherein adjacent layers ofsaid membrane structure are bonded toegether in a certain pattern ofbond lines, and the bonded structure being expanded to form saidhoneycomb structure.

2. The apparatus of claim 1 including, an array of tubular membersprojecting into opposite ends of one of said systems of fluidpassageways for manifolding said system of fluid passageways.

a m a s a I UNITED STATES PATENT OFFICE I CERTIFICATE OF CORRECTIONpatent-QM 7 9, Dated June 19 1973 Invent 0H5) H rry E. Aine It iscertified that error appears in the above-identified patent and thatsaidLetters Patent are hereby corrected as shown below:

T ,r p p T Insert following paragraph with heading on page 1, line 29:

RELATED CASES The subject matter of Figs. 14-16 is claimed herein; theremaining s ubject matter of this application is claimed in my copendingdivisional application U.S. Serial No.

360,800 filed May 16, 1973.

Signed a sealed this 2nd day ofJuly 1974.

(SEAL) Attest: I

EDWARD M.FLETCHER,JR. p C. MARSHALL DANN Attestlng Officerv Commissionerof Patents

2. The apparatus of claim 1 including, an array of tubular membersprojecting into opposite ends of one of said systems of fluidpassageways for manifolding said system of fluid passageways.